Electronically controlled micro-machined optical switches can be used to interrupt or redirect light output from an optical fiber. Such switches can be used in a variety of different applications in an optical communications system. For example, a low insertion loss optical switch with a high contrast ratio could be connected to optical fibers to allow a variety of adaptive, reconfigurable networks to be designed and constructed. Such switch would be used to direct light from a source fiber to different destination fibers. In the absence of additional focusing elements, the insertion loss of such a switch increases as the number of source and destination fibers increase. Such an increase in insertion loss is due to geometric constraints associated with standard optical fiber construction.
As an illustration of the above-described problem, consider an arrangement of four optical fibers, wherein the fibers are arranged end-to-end in pairs, with a gap between each pair of fiber ends. The two arrangements of paired fibers are disposed orthogonally to one another (and in the same plane) such that a gap between the fiber ends of both pairs overlap. In other words, the fibers are arranged at 0 degrees, 90 degrees, 180 degrees and 270 degrees. Since fibers are typically cleaved such that a flat or slightly angled face results, the ends of the above-described arrangement of fibers must be spaced from one another by at least one fiber diameter. Because a fiber typically consists of an optically active core having a cladding (required for support and to prevent undesired loss of light) of substantially larger diameter than such core, a gap of even one fiber diameter can represent a distance greatly exceeding the diameter of the core. Such a gap of one fiber diameter often results in an unacceptably high insertion loss due to the finite divergence of the optical signal. As such, the art would benefit from a low-insertion-loss arrangement of a micro-machined optical switch having at least four optical fibers.